Depression: chemical imbalance theory ‘not grounded in science’

A scientific review has concluded that depression is not caused by chemical imbalances in the brain, and may be more closely linked to stressful life events.

The review, conducted by University College London and published in the Molecular Psychiatry journal, examined the “serotonin theory of depression”, an “influential” and long-held belief that lower serotonin levels may make an individual more likely to experience depression.

A link between serotonin levels and depression was first put forward in the 1960s, and antidepressant use has increased since the 1990s with the development of Selective Serotonin Reuptake Inhibitor antidepressants. One in six adults in England are currently prescribed antidepressants, many of which help to adjust serotonin levels.

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“Many people take antidepressants because they have been led to believe their depression has a biochemical cause, but this research suggests this belief is not grounded in evidence,” said Professor Joanna Moncrieff, the study’s lead author.

The authors examined studies into the chemical’s impact on depression, including studies where participants’ serotonin levels were artificially lowered through dietary methods. In both cases, a link could not be established.

However, stressful life events were found to have a strong correlation to an individual’s risk becoming depressed. Some evidence also indicated that believing low mood relates to a chemical imbalance leads people to have “a pessimistic outlook on the likelihood of recovery, and the possibility of managing moods without medical help”, said The Telegraph.

Antidepressants “can work”, said the newspaper, but the researchers concluded it must be through a “different route”. They advised that doctors should not tell patients that depression is caused by a chemical imbalance, but experts have stressed that patients should continue taking their prescribed medication.